Linux Sudoers

The rules for which users/groups can use sudo are typically defined in the file /etc/sudoers. Typically, Linux distros will have a group which can use sudo, but the name of the group is not standardised across distros. Here are common default names for such groups:

Default Sudoer Groups:

Distro/s	Group Name
Red Hat Enterprise Linux, CentOS, Fedora, and their derivatives	wheel
Debian, Ubuntu, and their derivatives	sudo
Ubuntu (11.10 and earlier)	admin

WARNING: You should never edit /etc/sudoers directly - use the visudo command. (This will ensure that if your changes have any errors, they will be caught and reverted.)

Specify Permissions:

NOPASSWD

Allow the user example to use sudo without needing to enter a password by adding the following line to the end of the file

example ALL=(ALL) NOPASSWD:ALL

Instead of the user example, you can specify members of the group example by adding a percent sign to the beginning:

%example ALL=(ALL) NOPASSWD:ALL

Allow a Specific Command:

Allow the user example to use sudo without a password, but only when running reboot, halt, or poweroff:

example ALL=NOPASSWD: /sbin/reboot, /sbin/halt, /sbin/poweroff

WARNING: Giving limited sudo access to a user can still be dangerous, depending on the commands you give access - this should be considered a convenience, not a security control, unless you really know what you're doing.